title: The Am Gene Controlling Resistance to Alfalfa mosaic virus in Tomato Is Located in the Cluster of Dominant Resistance Genes on Chromosome 6.
abstract: ABSTRACT The dominant gene Am from Lycopersicon hirsutum f. sp. glabratum PI134417 confers resistance to most strains of Alfalfa mosaic virus, including the recently identified necrotic strains. The phenotypic response includes a lack of symptom development following mechanical inoculation of leaves. To study the resistance mechanism controlled by Am, biological (back-inoculation to susceptible hosts), serological (double-antibody sandwich, enzyme-linked immunosorbent assay), and molecular (reverse transcription-polymerase chain reaction and hybridization with specific riboprobes) methods of virus detection have been conducted on mechanically inoculated PI134417 leaves. The virus was never recovered, indicating that Am acts by an inhibition of viral accumulation during the early events of the virus life cycle. Am has been mapped genetically to the short arm of tomato chromosome 6 in the resistance hotspot, which includes the R-genes Mi and Cf-2/Cf-5 and the quantitative resistance factors Ty-1, Ol-1, and Bw-5.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Parrella
authors.forename: André
authors.initials: A
authors.lastname: Moretti
authors.forename: Patrick
authors.initials: P
authors.lastname: Gognalons
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Lesage
authors.forename: George
authors.initials: G
authors.lastname: Marchoux
authors.forename: Kashay
authors.initials: K
authors.lastname: Gebre-Selassie
authors.forename: Carole
authors.initials: C
authors.lastname: Caranta